Chapter 4.docx

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Information Technology Management
ITM 410
Margaret Plaza

Chapter 4 – Documenting Information Systems Reading Systems Documentation  Refer to figure 4.1 for Data Flow Diagram (DFD) Symbols on pg 104 Reading Data Flow Diagrams  Data flow diagram (DFD) is a graphical representation of a system o It depicts a system’s components, the data flows among the components & the sources, destinations & storage of data Context Diagram  Context diagram is a top-level or least a detailed diagram of a system depicting the system & all its activities as a single bubble & showing the data flows into & out of the system & into & out of the external entities o External entities are those entities outside the system that send data to or receive data from the system o Refer to figure 4.2 on pg 105 Physical Data Flow Diagram  Physical data flow diagram is a graphical representation of a system showing the system’s internal & external entities & the flows of data into & out of these entities o Internal entities is an entity within the system that transform data (ex. accounting clerks, departments & computers) o Physical DFDs specify where, how & by whom a system’s activities are accomplished but does not specify what activities are taking place  Refer to figure 4.3 on pg 106 and read the example Logical Data Flow Diagram  Logical data flow diagram is a graphical representation of a system showing the system’s processes (as bubbles), data stores & the flows of data into & out of the processes & data stores o Logical DFDs specifies what activities the system is performing without having to specify how, where or by whom the activities are accomplished o Advantage of a logical DFD  We can concentrate on the activities that a system performs (what the system performs instead of trying to figure out how, where or by whom)  Refer to figure 4.4 on pg 107  Logical DFDs are also known as level 0 diagram  When the context & level 0 diagrams have equivalent external data flows, then DFDs are balanced  Refer to figure 4.5 on pg 109 & read the example on pg 108 Reading Systems Flowcharts  Systems flowchart is a graphical representation of a business process including information process (inputs, data processing, data storage & outputs) as well as the related operations processes (people, equipment, organization & work activities) o It gives you a complete picture of a system by combining the physical & logical aspects o Systems flowchart includes the ope
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